Fig. 1

The figures illustrate the prepared endodontic access and Class II configuration in single-rooted premolars, as well as the location and size of the spacers used: (a) Occlusal view showing the endodontic access and Class II configuration. (b) Mesial view of the same preparation. (c) The guide was used to standardize the size of the PTFE spacer, ensuring it matched the size of a size 4 cotton pellet. The guide is a cotton-pellet-shaped resin mold. (d) PTFE is used as a spacer in the accessed endodontic cavity.